The ampersand glyph comes from the ligature of the letters e and t. It spelled the word et, which means and in latin, and in French. The two letters morphed with time into the one we know today.
There are virtually infinite variants on the design of the ampersand.
The word ampersand itself came from the combination of and per se. This happened because the & was actually considered the last letter of the alphabet. In school, young kids would say the alphabet, then end with:
pronounced and per say and. That last part eventually became the word ampersand. French esperluette may have a similar origin, et per lui et.
Use the word and in most scenarios. There are specific rules for when to use the ampersand. When several items are listed together, it will provide clarity to use the ampersand.
I packed a lunch that had fruit, milk and a peanut butter & jam sandwich
One of the most commonly seen uses is in company names.
Williams & Sons
Related to this would be the abbreviation,
Johnson & Johnson would be J & J